The invention relates to a switch box for railway, tramway points, or similar particularly of the so called english type, i.e. with four or more blades and in which the blades connect in pairs with the rails of a track, according the preamble of claim 1.
From WO 94/27853 a switch box which is used in combination with a simple switch with only two blades. In this switchbox only the operating groups, the groups of linear transmission of the operating motion and the groups locking the blades in the closed positions are located inside the box. At a central slide, housed in the box branch out drive rods to operate the blades which are external to the same. The group locking the blades in the closed position acts on the very slide and not on the blades, while no means are provided allowing kicking of the blades, that is, the disengagement of the same from the locking means, under the action of a preset force which operates on the blades in direction of displacement of the same.
A further switch box of the type described at the beginning but used in combination of ta simple switch with only two blades is known from the U.S. Pat. No. 4,093,163. In this case, also the link rods to the blades are housed in the box in shape of a sleeper, while neither means of lockswitching, nor means of kicking are provided.
The invention has the purpose to realize a switch box for railway, tramway points, or similar, particularly for the so called english type switch, and according to the preamble of claim 1, in such a way, whereby means are provided in the same suitable to guarantee one or more or all of the functions of locking, lockswitching and/or kicking of the usual switch boxes all the elements being mobile, with the exception of the blades integrated inside the box shaped like a sleeper, and the same being realized with an extremely simple construction, of reduced dimensions and such to ensure the housing in the defined available volume, as well as of safe and sure operation.
In particular, the invention aims at the realization of a switch box in which movable means of locking the blades in the corresponding position of closure are provided both by the linear transmission unit of the operating motion, as well as directly by the actual blades, all to reach the maximum operational surety and safety of the switch box.
The invention attains the above mentioned aims with a switch box.of the type according to the preamble of claim 1 and showing in combination the features of the characterising part of claim 1.
The switch box shows means for locking the blades in their closed position and which are automatically disengaged at the closed position of the opposite blade at the moment the switch box is activated to operate the blade.
The switch box, has means of linear transmission, formed by a saddle, slide or similar which are moved transversally to the track, particularly orthogonally to the same, in the two directions between the two extreme end of stroke positions by a group translating the rotary motion into a linear motion and to which are linked a transmission rod for each of the two blades, while each blade is connected to a lever coupling it to the respective transmission rod thanks to corresponding movable means locking the blade in the closed position.
In particular, the coupling levers of the blades corresponding to the transmission rods form said movable locking means of the blades.
According to an advantageus feature of the invention, the means of locking the blades in position of closure, are only associated with the outermost blades of the four blades provided, while each of the two internal blades is locked in position of closure thanks to a rigid mechanical connection with the external blade which assumes the closed position of the same together with the internal blades.
This arrangement allows to lock the inner blades of the switch, by mantaining all the units inside the box having the form of a sleeper.
The invention presents further features and perfectionings which are the subject of the claims below.
The features of the invention and the advantages derived from the same are better prooven by the following description of an executive example illustrated as non-limiting claim in the enclosed drawings, in where: